Between 1998 and 2011, the average price of works sold at auction increased markedly. Prices peaked in 2007, with the average price of works sold reaching $15,000 (64 percent higher than the 2006 average of $9,138).

Commentators suggest that speculation by investors led to a ‘market aberration’ in 2007.

Sales have since returned to pre-2007 levels. After the economic downturn in 2008, sales grew between 2009 and 2010, before stabilising in 2011 and 2012.